France's conservative UMP Party and its allies appear to have come first in the final round of departmental elections.
The UMP, led by former President Nicolas Sarkozy, appeared set to secure at least 65 local councils, exit polls suggested, up from 41.
Marine Le Pen's far-right National Front also appeared to have made gains, while the ruling Socialists and their allies may lose about 30 departments.
These elections are seen as a test case ahead of 2017's presidential election.
Paris and Lyon, France's two biggest cities, were excluded from Sunday's election.
The National Front appeared to have won a significant number of seats in Sunday's second round of elections, but did not appear to have gained control of any councils, the exit polls said.
Nonetheless, leader Marine Le Pen hailed a "historic" day for the FN, saying: "I thank all our voters for this magnificent success."
"The goal is near, reaching power and applying our ideas to redress France."
French Prime Minister Manual Valls admitted it was "incontestable" that the Socialist Party had lost ground.
"The French have declared... their anger at a daily life that is too difficult," he said. He vowed to redouble efforts to boost the economy, and said his focus was "jobs, jobs, jobs".
He added that the rise in the National Front's popularity was "a sign of a lasting upheaval of our political landscape and we will all need to draw lessons from it".
'Repudiation to Socialists'
Mr Sarkozy said voters had "massively rejected" the policies of his successor as president, Francois Hollande.
"Never has our political family won so many councils," he told supporters. "The repudiation of those in power is without question."
Mr Hollande has suffered from slumping personal ratings, boosted only briefly by his response to January's terror attacks in Paris.
One presidential adviser told AFP: "Everyone is scared they will be eliminated in the first round in 2017."
Bastions of the Socialists like the Nord department around Lille have swung to the right, as has President Hollande's own fiefdom of the Correze in central France, the BBC's Hugh Schofield in Paris reports.
However, as ever in France's two-round elections, voters from left and right united in round two to keep the National Front from power, our correspondents adds.
Turnout on Sunday was 41.94% at 17:00 (15:00 GMT), three hours before polls closed. Surveys suggested about 50% of those eligible took part in the polls, Le Monde reported.
Voters have been electing representatives in 101 departments, or counties, in the two rounds of the local elections. The departments are charged with issues like schools and welfare.